Bandpass reaction cell inductively coupled plasma mass spectrometry for the determination of silver and cadmium in samples in the presence of excess Zr, Nb and Mo

An inductively coupled plasma quadrupole mass spectrometer (ICP-QMS) equipped with a Dynamic Reaction Cell(TM) (DRC) was used to reduce the oxide interferences for the accurate determination of Ag and Cd in samples in the presence of excess Zr, Nb and Mo. The effect of the operating conditions of the DRC system was studied to obtain the best signal to noise ratios for Ag-109 and Cd-111. The potentially interfering polyatomic ions (NbO+)-Nb-93-O-16, (ZrOH+)-Zr-92-O-16, (MoOH+)-Mo-92-O-16, Mo-95(16) O+, (ZrOH+)-Zr-94-O-16 and (MoOH+)-Mo-94-O-16 on Ag-109(+) and Cd-111(+) determination were decreased in intensity to an insignificant level by using O-2 as the reaction gas. Furthermore, a rejection parameter q (Rpq) of 0.6 was used to filter out unwanted precursors of interfering species from the ion beam to eliminate interferences created in the reaction cell. The detection limit was ca. 2 and 3 pg ml(-1) for Ag-109 and Cd-111, respectively, with the DRC ICP-MS method. The method was applied to the determination of Ag and Cd in NIST SRM 2709 San Joaquin soil reference material as well as NIST SRM 1568a rice flour reference material. The precision between sample replicates was better than 5.7% and the analysis results were in good agreement with the expected values. (C) 2003 Elsevier B.V. All rights reserved.